Hello all, thanks in advance for reading. I've been doing a bit of research on my own on these forums as well as others. The TSB sticky on here has great information, but to be honest it seems like my issue could be originating from so many things. Here's the story:

The engine will crank but not start. I have been seeing several intermittent messages for a while on the dash that I can list: TRAC Not Available, ASC Not Available, Check Rear Lights, a warning about ABS, Brake Fluid Low, Coolant Low, and now very recently Failsafe Engine Mode. The coolant warning goes away when I top it off. The Check Rear Lights warning I assume is just something stuck in memory, because I did have a dead brake light that I replaced. I have also occasionally experienced vibration in the brake pedal and in the steering wheel while making turns (not always brake pedal and steering wheel vibration felt together, but sometimes together).

It has been exceptionally cold in my neck of the woods (single digits, sometimes below 0 F). For the past two weeks the engine has had rough starts but would always turn on after 1 or 2 seconds. After I did not run the engine for about 3 days it will not turn on at all. The engine has always started without a hitch before this, so it is a very new problem. Here are the things I have tried already: Jumping old battery, installed new battery, and tried starting engine while in N. I also installed all new pre-gapped Bosch spark plugs. I didn't do that because of this issue, but should still be seen as pertinent information.

So my issue is figuring out why the engine will not turn on. I've been able to piece together from other threads that it could be a dirty sensor on the throttle body, the throttle body itself may be causing the issue, the brake pedal switch, or any one of the myriad of electrical issues possible. I do not have a code reader, so I'm sorry that I can't provide any type of technical diagnostic information. I may look into borrowing or purchasing a code reader and post the codes. Thanks again.

 

A long list of codes like that usually points to a battery fault, which can be hard to diagnose. You get a whole heap of error codes because the sensors don't have enough voltage to take a proper reading. Have you tried replacing the battery properly, rather than just jumping it?

You really need to check it with a code reader though, as there may be something there telling you exactly what the fault is, rather than guessing.

 

I agree about the codes. I replaced the battery with a new one (the old one looked like the factory battery) but the issue remained.

 

There are several connections for both the + hot and - ground systems. Start at the battery pos. and check at the two big fuses in the trunk. Make sure the connections are clean and tight, then in the engine compartment there are bulkhead connections to check. A big source of trouble is the engine to frame ground at the back of the bellhousing under the car.
Obviously, there are many other possible problems, and without a code reader it's not easy to narrow down the search.

 

I think you should measure the fuel pressure- A cheappy test guage is about $50.

 

I come bearing codes! P1642 & P1111.

 

I'm reading that P1642 points to a CAN circuit malfunction, which doesn't narrow it down too well. I understand that P1111 just means that diagnostic tests have been completed, so it's not much help.

 

P1642 is often caused by a protocol issue between the code reader and the ECM. It could also indicate a bad connection in the CAN circuit, which is the communication system for all the modules and the transmission switches.

 

Something else I noticed while changing my spark plugs was that one of the rubber sheaths on an ignition coil was torn. It was already torn prior to this issue, but I accidentally made it worse with a pair of needle nose pliers trying to fish it out of the well after it was stuck down in there. Would this cause any dissues? I'm going to research which connectors needs to be cleaned, as well as any fuses or relays that need attention. I'll keep you all updated. Thank you for the responses so far.

 

Click on the link in my signature, it has the info needed to troubleshoot the common electrical problems. Good luck!

 

Thanks a lot! This helped to narrow down some of the possibilities. All measurements were done with the engine off and the ignition in the ON position. The battery measured 12.04 V. All of the studs in the High Power Protection module hovered just over 12 V each. I checked the false bulkhead stud connector and found it to be squeaky clean. As I was about to measure its voltage, I noticed something deep in the corner of the passenger side of the engine compartment; what appears to be a rat's nest. It looks like insulation, assorted fabric, and twine in there. So I'm thinking that it's definitely an electrical issue, more than likely some wires chewed by rodents making a home in my Jag. The @$%!%!!!!!

Weather permitting, I will also check the ground strap cable as well as the other "engine won't crank" checklist items. Thank you all for any additional input.

 

You're welcome! Post some pictures of the damage if possible. Is it near the headlights?

And just to be sure, does it crank over at all? Or just click?

 

It cranks. I haven't found any solid evidence of damage yet, but with the remnants of the nest I assume that any existing damage has likely been caused by rodents. I'll try to upload pictures when I find definitive proof. The nest is back towards the windshield/windscreen. So it's the corner of the engine compartment behind the false bulkhead, right around the passenger side view mirror.

A major complication is that I still work a full time job, so once I get home there is only about 1.5 hours of daylight left. Plus it's been as cold as the dickens outside (high of 21 F today), so the snow and ice has yet to melt, making it difficult to survey the undercarriage of the vehicle. If there is a starting point any of you can recommend in checking wiring that Mickey Mouse would have chewed up, it would help a great deal. Thanks again

 

Go here, and download the wiring diagrams for your car. (Basically the link is the document, just save it to your computer somewhere). It has all sorts of good info, including where the modules and harnesses are.

http://www.captainjaguarscathouse.co...ec%20Guide.pdf

 

Now that I'm looking at the Main Power Distribution schematic, my suspicion is that a wire has been damaged between the HPP module and the false bulkhead connector, which itself is connected to the starter. I'll confirm and let you all know the verdict...

 

I would look elsewhere- It would not crank if that conductor was damaged. You did say it cranked, did you not? That would mean the starter circuit is not your problem.

Spark, Fuel, Air, in the righ proportions, at the right time. Which one are you missing?

 

You're definitely right about that. I'm not sure what I was thinking. Yes, it does crank. The spark plugs that are installed right now are brand new, but I was having the issue before I changed them out (not because of the issue, but rather part of general maintenance). That leaves the throttle body and fuel pressure to check. Is it necessary to check on the related fuses and relays as well? I apologize for all of the questions; I have a rudimentary understanding of electrical systems, but I learn quickly. Thanks

 

Well, unfortunately the three horsemen are easy to write, but not so easy to make sure they are there!

The rats eating a wiring harness seems like a reasonable connection between the several symptoms you mentioned, or a power supply fuse or relay. On the other hand, it sounds like some of the problems have been accumulating over time, and now the failure to start has happened, not necessarily related to the other problems.

I think you should check every fuse in the five fuse blocks. That might give you a clue as to where the rats found their nest material. You also need to give a good visual inspection. With any luck, they really didn't eat your car!

Have you considered that you might have cylinder wash? Check the archives.

You can check the spark by removing a coil, inserting a spare spark plug in the boot, and laying it on top of the valve cover. Crank and check for spark.

You can check for at least some fuel pressure by depressing the Schrader valve after cranking and see some gas squirt out. Do this AFTER the spark test mentioned earlier for obvious reasons!

I live in the south, so I am not experienced in fuel icing issues, but it seems like you might have some of that. If you can get a fuel pressure test gauge, you can answer a number of questions.

Another question. When you say no start, does it seem to crank over smoothly, or does it occasionally seem to fire? Is it cranking "smartly" with about 200 rpm showing on the tach?

If you don't find it pretty quick, unfortunately, you probably need to consider letting someone with some diagnostic equipment have a go,

Good Luck!

 

12.04 volts is very low, should be about 12.6. I suggest putting battery on charger overnight, see if that gets rid of your problems.

 

I don't believe that it's cylinder wash. I performed the recommended treatment of injecting oil into the cylinders, pressing the accelerator to the floor, and then turning the key for a few seconds. Nothing. I'm going to check fuel pressure next.